Air Quality

The progressive degradation of the wastes disposed of in landfill sites generates landfill gas which is largely a combination of methane (approximately 60%) and carbon dioxide (approximately 40%). There are also trace components such as hydrogen sulphide which can cause landfill gas to become odorous. In a hazardous waste landfill the quantity of landfill gas is much less than a typical domestic waste landfill but ENRMF still has full gas control systems to ensure that any gas generated is appropriately managed.

At ENRMF air quality is monitored in the surrounding boreholes and in the ambient air on a monthly basis.

Below are presented graphs showing the available results for the last 12 months of monitoring of methane in boreholes and the ambient air and hydrogen sulphide in the ambient air.

Methane in boreholes
Methane is monitored in boreholes to confirm that landfill gas generated in the landfill is not migrating from the site into the surrounding ground.  Methane is not toxic but it is a greenhouse gas and is flammable so it must be controlled.  Methane can however be generated by the breakdown of vegetation hence detection of the gas must be interpreted in the context of the surrounding environment.  A trigger level of 1% methane has been set by the Environment Agency which is well below a concentration of concern.
















The results show that there is little Methane in the groundwater boreholes and all results are well within the trigger value.

Ambient methane

The purpose of monitoring ambient methane is principally to confirm that significant amounts of this greenhouse gas are not escaping from the site.  Ambient methane is measured by walking around the site boundary with a hand held meter.  The concentration is measured in parts per million (1ppm = 0.0001%).
















The graph shows that no ambient methane levels have been detected above the permitted trigger limit of 10ppm at any of the ENRMF site boundaries during October 2013 through until March 2016   

Ambient hydrogen sulphide
Hydrogen sulphide is the cause of the smell of rotten eggs. At high concentrations it can be poisonous.  It is monitored largely because of its odour generating potential as the smell is noticed at a very low concentration. Ambient hydrogen sulphide is measured by walking around the site boundary with a hand held meter.  The concentration is measured in parts per million (1ppm = 0.0001%).  Hydrogen sulphide is only measured if ambient methane levels are elevated above the permitted trigger limit.  No elevated levels of ambient methane have been recorded so it has not been necessary to monitor hydrogen sulphide.

If you have any queries relating to this information or would like to be kept informed of developments at ENRMF please contact us at or telephone us on 01904 654989 to be added to our register of stakeholders.